Polygonal Centering Pin for Watch Bridge Positioning
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Solution Overview
Problem
In watchmaking, precise mounting of components like bridges on plates is challenging due to differential expansion and deformation, leading to compromised positioning precision and rigidity, especially when components are manufactured separately, requiring tight tolerances and resulting in difficulties during assembly and disassembly.
Innovation Solution
A centering pin with symmetry of revolution is used in conjunction with a female centering implantation on the plate, featuring a polygonal or star-shaped section that rests on at least three facets, ensuring precise centering and alignment while allowing for disassembly, utilizing a method that includes pre-centering and immobilization to maintain precise positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a clearance is provided between the male centering means and the female centering means to ensure assembly and disassembly, then the ease of operation is improved, but the positioning precision and rigidity of the support are compromised
Solution Approach 1:
The invention replaces the symmetric cylindrical centering means with an asymmetric polygonal centering means (triangle, square, or star-shaped) that has flat facets. This asymmetric geometry creates specific contact points between the centering pin and the bridge, eliminating radial play while maintaining the ability to assemble and disassemble the components. The asymmetric shape ensures that the bridge can only be positioned in one precise orientation relative to the plate.
2Manufacturing precision
If tight manufacturing tolerances are assigned to respect the distances between two centering elements when components are made separately, then the positioning precision is improved, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The asymmetric polygonal centering means serves as a self-aligning feature that guides the bridge into the correct position during assembly. The flat facets of the polygonal shape provide natural reference surfaces that simplify the alignment process, eliminating the need for complex adjustment mechanisms or extremely tight tolerances on multiple dimensions. The geometry itself encodes the positioning information.
Solution Approach 2:
The asymmetric polygonal centering means automatically performs the alignment and positioning function during assembly without requiring external adjustment or complex manufacturing processes. The geometry of the facets self-corrects minor misalignments and ensures precise positioning through the natural mechanics of the fit between the centering pin and the polygonal shape.
3Adaptability or versatility
If the components are manufactured separately instead of simultaneously on the same manufacturing means, then the adaptability is improved, but the positioning precision deteriorates due to differential expansion and deformation
Solution Approach 1:
The asymmetric polygonal centering means creates a unique fit that compensates for variations in manufacturing tolerances and material deformation. The flat facets provide stable contact surfaces that are less sensitive to thermal expansion and deformation than point contacts or cylindrical surfaces. This geometry maintains precise positioning even when components are manufactured separately using different processes or at different times.
Data Source
Figure 1~8
AI summary
The device has female areas of support (5) that is spaced equidistantly about linear axis. A ribbed female centring housing (4) is arranged to receive smooth centring pin (6) fixed to bridge (2), and abutted on female areas of support. A smooth female arrangement is arranged to receive ribbed centring pin, and abutted on male areas of support. An alignment housing (8) with parallel faces (9,10) is aligned on female arrangement in direction relative to directional axis of centring housing. Independent claims are included for the following: (1) timepiece; and (2) method of assembling bridge on plate using centring and alignment device.